This invention relates to circuitry for supplying drive power to any of a number of paths. More particularly, it is concerned with drive circuitry including arrangements for determining if the proper number of paths are being driven.
Crosspoint switching arrays employing solid state devices have been developed for use in switching networks of communication systems. An array of switching circuits employing solid state devices is described and claimed in U.S. Pat. No. 3,826,873 entitled "Switching Circuit Employing Latching Type Semiconductor Devices and Associated Control Transistors" which issued on July 30, 1974 to A. Frederick Susi and is assigned to the assignee of the present invention. As described in the patent to Susi a switching circuit of an array is connected to one control line in each of two sets of control lines. An individual switching circuit is activated to permit the transmission of signals by the simultaneous application of momentary pulses of opposite polarity on its two control lines. The two sets of control lines, one for positive-going control pulses and the other for negative-going control pulses, are connected to the switching circuits of the array so that only one switching circuit is selected when a positive-going pulse is applied to one of the control lines of one set and a negative-going pulse is applied to one of the control lines of the other set.
In switching arrays of the foregoing type it is desirable before accomplishing the activation of a switching circuit during a switching operation to ascertain that one and only one switching circuit is being selected. That is, it is desirable to be able to determine that a control pulse will be present on one and only one positive-going control line and also that a control pulse will be present on one and only one negative-going control line. Thus, it is assured that one and only one switching circuit of the array will be activated during the switching operation to permit the transmission of signals therethrough.